CN104140102A - Adhesive for preparing silicon smelting waste carbon-containing pellet and preparation method of pellet - Google Patents

Abstract

The invention provides an adhesive for preparing a silicon smelting waste carbon-containing pellet. The adhesive comprises 70wt% to 90wt% of water-soluble silicate (potassium silicate or sodium silicate or mixture of the potassium silicate and the sodium silicate) and 10wt% to 30wt% of organic ignition-lost type material. The invention also provides a method for preparing the pellet by using the adhesive according to claims. The method comprises the following steps: mixing the adhesive with water, then mixing the mixture with a pellet material, rolling into pellets under the pressure of 20MPa to 40MPa, wherein the addition ratio of the adhesive is 2% to 8% of the pellet material. The adhesive disclosed by the invention has the advantages of being low in price and small in used amount, simultaneously increasing the low-temperature strength and high-temperature strength of the silicon smelting waste carbon-containing pellet and the like.

Description

For the preparation of the binding agent of refining silicon waste carbonaceous pelletizing and the preparation method of pelletizing

Technical field

The invention belongs to exploitation and the Application Areas of adhesive for carbon-containing pellets, be specifically related to a kind of for refining the binding agent of silicon waste carbonaceous pelletizing and the method for pelletizing.

Background technology

In tradition refining silicon technology, raw material is by silica (SiO ₂) and reductive agent (charcoal, refinery coke etc.) form, refining silicon process is produced continuously in Semi closed electric furnace, the heat that in smelting process, electric current produces by electrode and charging resistance and the arc heat of electrode tip are heated to furnace charge more than 2000 ℃, at this temperature, silicon-dioxide has been generated Pure Silicon Metal liquid through a series of physical-chemical reaction by carbon reduction, and overflows with CO gas and SILICA FUME.

Yet in the normal running of refining silicon electric furnace, especially large and medium-sized electric furnace, requires furnace charge to have suitable lumpiness to guarantee good ventilation property.Therefore the silica and the charcoal that, enter stove will have certain granularity requirements.Generally, the granularity of silica is controlled at 40-120mm, and charcoal granularity is controlled at 20-200mm.This just requires will to carry out fragmentation, screening to silica and reductive agent in the raw material preparatory stage, to meet the granularity requirements into furnace charge.

The refining such as the bitstone that can not enter stove (granularity <40mm) producing in crushing and screening process and wood fragments charcoal (granularity <20mm) silicon waste enormous amount.According to statistics, bitstone will account for the more than 35% of total silica amount, and wood fragments charcoal also will account for 20% left and right of charcoal amount.These refining silicon wastes are idle, caused the very large wasting of resources, and this waste improves the relative cost of unit output greatly; And in smelting process, also have a large amount of solid waste SILICA FUME (ω (Si) >=95%) to produce, and if the insufficient utilization of these SILICA FUME also can cause a large amount of wastings of resources and production cost to rise.In addition, in smelting cost, consider, the price of charcoal is relatively high, if can use the relatively cheap refinery coke of price or graphite to replace part charcoal, also can make to refine silicon cost and decline to a great extent.But the Relative Size of refinery coke and graphite is thinner, directly into stove, can affect the ventilation property of electric furnace.

For waste material (as bitstone, wood fragments charcoal) and the siliceous dust of by product (SILICA FUME) tradition being refined in silicon process fully utilized in conjunction with appropriate low-cost material (as graphite, refinery coke), expand raw material sources and save production cost, applicant provides a kind of novel process of refining silicon waste carbonaceous pelletizing refining silicon, this technique is according to electric furnace Production requirement, refining silicon waste is carried out to pre-treatment, batching, pelletizing, oven dry, directly add electric furnace refining silicon.In order to make to refine carrying out smoothly of silicon production, must guarantee that these waste carbonaceous pelletizings have certain low temperature intensity and hot strength, particularly crucial but the exploitation of suitable binding agent seems.

In recent years, the preparation of the organic binder bonds such as the mineral binder bonds such as wilkinite and starch, silicone resin has all obtained research to a certain degree with use, and it relates generally to the preparation technology that field is iron ore carbonaceous pelletizing.Result of study can be summarised as substantially: mineral binder bond balling property is good, resource is sufficient, but easily introduces impurity element, affects pellet quality; And the cementing properties of organic binder bond better, combustion decomposition under high temperature, do not affect pellet quality, but consumption is restricted, otherwise can reduce pelletizing ultimate compression strength and burst temperature.The exploitation of the binding agent of better performances is used with reasonable: or use outstanding single binding agent advantage by optimization, or obtain mutual supplement with each other's advantages by reasonably combined nothing/organic binder bond, be all the problem of worth synthetic study.Be conceived to refine silicon waste carbonaceous pelletizing preparation technology, it is valuable correspondingly developing a kind of binding agent and using method thereof.

Summary of the invention

The present invention aims to provide and a kind ofly for refining the binding agent of silicon waste carbonaceous pelletizing and rational using method, guarantees to prepare intensity qualified, and quality meets the pelletizing into stove requirement.

Binding agent provided by the invention comprises water-soluble silicate 70～90wt%, has machine burning to lose shaped material 10～30wt%.

Wherein, described soluble silicate at room temperature and between refining silicon waste powder particle surface can form one deck adhesive film.The silicic acid adhesive film that this one deck is very thin makes to interconnect between powder particle, and the room temperature strength of carbonaceous pelletizing is improved; Along with the further rising of temperature, silicate precipitated silicic acid gel particle is filled in the pore in carbonaceous pelletizing, is conducive to the raising of intensity; Under hot conditions, the Si-O-Si bond energy that silicic acid gel forms enough connects into network-like structure by gel particle and powder particle, can play settable cementitious effect; Silicic acid gel is dry, due to the existence of high temperature resistant elemental silicon with and network-like structure, also can make pellet strength further improve; Select water glass as binding agent, can not bring a large amount of impurity elements, and the Na in silicate, K etc. can play promoter action to the reduction of silica.

Preferably, the described machine burning mistake shaped material that has comprises starch 0～20wt%.

Described starch at room temperature has water swellability and toughness, is conducive to refine the raising of silicon waste carbonaceous pelletizing green ball strength; When temperature raises gradually, starch starts gelatinization, and after gelatinization, the blend blending of starch and waste powder particle has improved the compactness of pelletizing, has further improved the intensity of carbonaceous pelletizing; Along with the further rising starch dehydration formation solid phase cross structure connection of temperature, but the volatilization gradually under hot conditions of solid phase cross structure is unfavorable for the raising of the hot strength of carbonaceous pelletizing.

Preferred, described organic burning-loss material also comprises one or more in silicone resin, epoxy resin and carboxymethyl cellulose chlorins compound.

Described carboxymethyl cellulose chlorins compound etc. is granular or fibrous material, strong, the soluble in water formation colloidal solution of its water absorbability; Contain-COO-can form chemisorption with refining silicon waste powder particle surface, and-OH is good hydrophilic radical, can effectively improve the wetting ability of binding agent.Between refining silicon waste powder particle and reductive agent, by the contour molecule organic chain of carboxymethyl cellulose chlorins compound, combine, by the adhesive capacity between adhesive particle, form the chain shelf structure with some strength, therefore add the binding agents such as carboxymethyl cellulose chlorins compound to be beneficial to the raising of carbonaceous pelletizing intensity; The binding agents such as carboxymethyl cellulose chlorins compound coordinate with starch in certain ratio range, can make the adhesive property of binding agent be improved.While contacting with powder particle, increase the bonding force between them, thereby improved pellet strength.

The present invention also provides a kind of preparation method of pelletizing, comprising:

Binding agent is mixed with water, then mix with pelletizing feed, under 20～40MPa pressure, be pressed into ball; The interpolation of described binding agent is than being 2～8% of pelletizing feed.

Preferably, binding agent and water, then compacting balling-up after mixing with silicon-containing material and carbon raw material, described silicon-containing material at least comprises a kind of in silicon-containing material SILICA FUME or ground silica, described carbon raw material comprises one or more in wood fragments charcoal, refinery coke and graphite.

That binding agent provided by the invention has is cheap, usage quantity is little, can improve the advantages such as refining silicon waste carbonaceous pelletizing low temperature intensity and hot strength simultaneously.

Embodiment

Below in conjunction with specific examples, the present invention is carried out to concise and to the point supplementing and effect commentary, the refining silicon waste wherein using in carbonaceous pelletizing main body batching is bitstone, wood fragments charcoal, SILICA FUME; Low-cost material is selected graphite, refinery coke.

Embodiment 1

Select water glass and starch to prepare adhesive for carbon-containing pellets according to the ratio of massfraction 85% and 15%, according to the usage ratio of mass percent 4%, coordinate 7% water, mix with refining silicon waste powder and low-cost material, sending into and setting into ball pressure is that the pair roller ball press of 30MPa is suppressed.After dry, the strength test result of pelletizing is as follows:

Embodiment 2

Water glass, starch and Xylo-Mucine (CMC-Na) are prepared to compound binding agent according to the ratio of massfraction 76%, 20%, 4%, by the binding agent preparing according to 4% proportioning, water with addition of 8%, mix with refining silicon waste powder and low-cost material, sending into and setting into ball pressure is that the pair roller ball press of 30MPa is suppressed.Pellet strength test result is as follows:

From above-mentioned intensity data, the dried dropping strength of carbonaceous pelletizing, ultimate compression strength, barrate strength and the hot strength of preparation are all very high, 1.5m dropping strength is all more than 5 times, ultimate compression strength is all more than 400N, barrate strength is all more than 98.5%, the hot strength of 1400 ℃ all, more than 1000N, can meet refining silicon needs completely, and have larger improvement than existing binding agent effect.

Claims (5)

1. for the preparation of a binding agent for refining silicon waste carbonaceous pelletizing, it is characterized in that, described binding agent comprises water-soluble silicate 70～90wt%, has machine burning to lose shaped material 10～30wt%.

2. binding agent according to claim 1, is characterized in that, described water-soluble silicate is potassium silicate or water glass, or its mixture.

3. binding agent according to claim 1, is characterized in that, the described machine burning mistake shaped material that has comprises starch 0～20wt%.

4. binding agent according to claim 3, is characterized in that, described organic burning-loss material also comprises one or more in silicone resin, epoxy resin and carboxymethyl cellulose chlorins compound.

5. utilize the arbitrary described binding agent of claim 1～4 to prepare a method for pelletizing, comprising:

Binding agent is mixed with water, then mix with pelletizing feed, under 20～40MPa pressure, be pressed into ball; The interpolation of described binding agent is than being 2～8% of pelletizing feed.